Effect of Rescanning Strategy on Residual Stress and Distortion of Two Alloys Manufactured by Selective Laser Melting

During selective laser melting (SLM) process, high cooling rate and large temperature gradient result in residual stress and serious distortion, which seriously affect mechanical properties and dimensional accuracy of the final part. Rescanning strategy is recently proposed to reduce the stress and distortion during SLM process. However, the method was validated to enhance the residual stress and distortion by testing the distortion of two kinds of alloys manufactured by SLM in the work. Twin-cantilever specimen and thin-wall specimen were designed to evaluate the degree of the residual stress and distortion, respectively. Results showed that the residual stress and distortion of all specimens subjected to rescanning strategy were more serious than those of specimens without rescanning strategy. In addition, the degree of residual stress and distortion increased with the rescanning power increasing. The study tried to explain the reason of the difference by constructing the model of thermal expansion and cold shrinkage of the part during SLM process.

Automated summary

The rescanning strategy proposed to reduce stress and distortion during SLM process was found to actually enhance residual stress and distortion in this study. Residual stress and distortion were more serious in specimens subjected to rescanning, with the degree increasing with rescanning power. Construction of a thermal expansion and cold shrinkage model was attempted to explain the reasons behind the differences observed.